A rail-fastening system of analogous type is revealed DE 34 00 110 [U.S. Pat. No. 4,770,343] in which the railroad rail is secured by the screw, anchor, angle guide plate, and clip. A clip is used here that is provided between an angle guide plate (retention plate) and a screw (fastening anchor) when in the installed state. The clip here has two arms that are configured as torsion elements. The torsion arms have two parallel adjacent flexible rod sections that are connected together as a single piece by a loop that forms a clamping section and is essentially bent outward perpendicular to them.
A rail-fastening system of this type must solve two problems:
First, it is desirable to be able to fix different rail types (for example, type U 50 and type UIC 60) having different rail foot widths to different types of concrete sleepers using only one type of clip. The adaptation can be effected here by different angle guide plates.
Secondly, it is advantageous in terms of a simple, cost-effective and reliable installation of the rail-fastening system if the installation can be performed by sliding the clip from a preinstallation position (with the screw tightened with a torque of approximately 50 Nm) to a final installation position. It is important here to be able to easily slide the clip without having previously loosened the screw (pretightened with the above-mentioned torque). It is furthermore important that no lifting of the railroad sleeper be required here, an action that would make installation significantly more difficult. This is the only way installation can be automated.
Another aspect that is also of key importance to this invention is that the rail-fastening system be of high electrical resistance. This resistance is measured between the two rails on a concrete sleeper in the wet state, that is the value of the resistance is measured when exposed to a continuous rain. The rail is typically insulated from the railroad sleeper by the plastic anchor for the screw, the rail pad that is composed of rubber or plastic, and the plastic angle guide plate. This type of insulation is completely sufficient when dry. When wet (that is when exposed to rain), this insulation is not sufficient since water flows into the gaps and cracks in the rail-fastening system. The region of the anchor is especially affected as water flowing into the anchor results in a short-circuiting of its electrical resistance. The prior art remedies this by filling grease (for example Elaskon) into the anchor before insertion of the screw. The insulating effect is provided only to a limited extent since this action is performed during irregular construction operations and also since the grease hardens after a certain period of time. The previously known rail-fastening systems thus still have vulnerabilities in terms of this range of problems to be solved.